The present invention relates to methods and nucleic acid compositions for the production of transgenic plants resistant to nematodes. In particular, it relates to nematode-resistant transgenic plants comprising sequences from nematode-induced genes.
Plant parasitic nematodes significantly affect the productive capability of the world's farmlands. They reduce the yield of the world's forty major food staples and cash crops by an average of 12.3%, with losses substantially higher for some commodities (e.g., 20.6% for tomato). In the U.S. the reduced yields cause losses of $5.8 billion annually.
Especially significant in terms of crop losses are the sedentary endo-parasites, cyst nematodes (Globodera spp. and Heterodera spp.) and root-knot nematodes (Meloidogyne spp.). Cyst nematodes generally infect potatoes, soybeans, sugar beets, and wheat. Root-knot nematodes affect over 2,000 species of plants, including most of the major crops in the world.
Root-knot nematodes and cyst nematodes have similar life-cycles. Infection occurs after larvae hatch in the soil, invade the root and migrate intercellularly to the developing vascular cylinder where permanent feeding sites are established. Mature feeding sites are characterized by the presence of multinucleate cells, termed "giant cells" in root-knot nematode infections and "syncytia" in cyst nematode infections. These large, avacuolate cells with extensively remodeled cell walls are metabolically active and serve as the obligate nutritive source for the developing nematode. Giant cell formation, coupled with limited proliferation of nearby pericycle and cortical cells results in the characteristic root-knot gall.
Today, nematode infections are controlled primarily using chemical nematicides. These compounds are generally very toxic and have been suspected of causing environmental damage. These concerns have prompted efforts to find other methods of controlling nematodes in economically important crop plants. The present invention addresses these and other needs.